Seven taxi firms have been suspended in Hanoi and Ho Chi Minh City as their lax management allowed drivers to overcharge customers.

The suspension was made after nearly a month of investigation by the Transport Ministry, news website VnEpxress said Tuesday.

Six firms in Hanoi had their licenses revoked.

The one firm suspended in HCMC was the Tourism Vehicle Cooperative No.2, which operated tens of taxi cabs but had no system of managerial oversight.

Nguyen Xuan Hao, chief inspector of the ministry, said, "The cabs do not have walkie-talkies, thus their managers could not summon them to the headquarters when the inspectors wanted to check the cars."

Hao said the company does not keep records about their drivers either.

During the inspection, Vietnam's major transport corporation Mai Linh was also found to violate taxi management codes. Two of its cabs were running with meters that had not been checked regularly.

The ministry will continue to monitor taxi management at seven companies in HCMC, including Vietnam Taxi Company, the popular transport firm Phuong Trang, Anh Duong Vietnam that operates Vinasun cabs, and Gas Saigon, a member of Vietnam's leading gas retailer Petrolimex.

There're 108 taxi firms operating in Hanoi with more than 16,000 cabs. HCMC has only 35 firms, but with more cabs, the report said.